JPH05194841A - Polyamide resin composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition which is good in flow and mold release, is markedly improved in productivity because of its short molding cycle and can give a molding having a good appearance and excellent mechanical properties and especially being highly rigid yet tough. CONSTITUTION:The objective composition comprises a polymide (A), a polyamide oligomer (B) terminated with a 5-30C hydrocarbon group and having a molecular weight of 5000 or below, an inorganic nucleator (C) and a metal salt (D) of a fatty acid, wherein 0.001-10 pts.wt. component B and 0.005-5 pts.wt. total of components C and D present per 100 pts.wt. component A.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polyamide resin comprising a polyamide resin, a polyamide oligomer, an inorganic crystal nucleating agent and / or a fatty acid metal salt, and having excellent high cycle properties and mechanical properties, particularly bending and bending resistance at low temperatures. It relates to a composition.

[0002]

2. Description of the Related Art Polyamide resins are widely used as engineering plastics because they have excellent mechanical properties as well as abrasion resistance, electrical properties, chemical resistance and workability. However, with the advancement of industry, the physical properties required for polyamide resins have also improved,
And diversified.

In recent years, representative of the advanced and diversified required characteristics are improvement of high cycle property and improvement of mechanical characteristics at low temperature. If the high cycle property is improved, the molding cycle can be shortened and the productivity can be improved.

The means for improving the high cycle property can be achieved by increasing the crystallization rate of the polyamide resin or by improving the releasability from the mold.

In order to improve the crystallinity of polyamide resin,
A method of adding an inorganic crystal nucleating agent represented by talc. Further, for the purpose of improving releasability and plasticizing property, a polyamide is added with ethylenebisamide (Japanese Patent Publication No.
9825), bisureide (Japanese Patent Publication No. 48-6177, Japanese Patent Publication No. 53-126056), stearic acid ester (Japanese Patent Publication No. 55-31803), and aliphatic carboxylic acid substances (Japanese Patent Publication No. 54-103460). JP-A-49-9618) and a method of adding an amide compound (JP-B-49-9618) for the purpose of improving fluidity.

Further, with the diversification of application and development of polyamide resins, there is a demand for improvement of low-temperature mechanical properties represented by bending bending resistance at low temperatures. As a method for improving this, it has been proposed to block the ends of polyamide by 40% or more (Japanese Patent Publication No. 3-23093) and 55% or more (Japanese Patent Publication No. 3-23094).

[0007]

However, the above-mentioned method aimed at improving the mold releasability and plasticizing property is not yet satisfactory in shortening the molding cycle and improving the mold releasability. There is also a problem that the toughness represented by the elongation is significantly reduced.

For example, when talc is added as a nucleating agent, there is a problem in that although the crystallization rate is certainly improved, the toughness is also lowered, and so-called protruding pin is apt to be deformed. This problem has not always been improved by simultaneously adding the inorganic crystal nucleating agent and the releasing agent.

Although the method of blocking the ends of the polyamide certainly improves the low-temperature bending property and the releasability, it cannot be said that the productivity is so good because the rigidity is lowered and the degree of polymerization is hard to increase.

Therefore, the present invention aims at obtaining a polyamide resin composition for injection molding which is excellent in mechanical properties, especially bendability at low temperature, and rigidity while further improving fluidity, crystallinity and mold releasability. It is an issue.

[0011]

That is, the present invention is as follows.
A composition comprising (A) a polyamide resin, (B) a polyamide oligomer having a hydrocarbon group having 5 to 30 carbon atoms at a terminal and having a molecular weight of 5000 or less, (C) an inorganic crystal nucleating agent, and (D) a fatty acid metal salt, (A) 100 parts by weight, (B)
0.001 to 10 parts by weight of (C) + (D) 0.005
A polyamide resin composition composed of 5 parts by weight is provided.

That is, the present inventors have found that when a polyamide oligomer is blended with a polyamide oligomer and an inorganic crystal nucleating agent, or when a polyamide resin is blended with a polyamide oligomer and a fatty acid metal salt, or a polyamide resin is blended with a polyamide oligomer and an inorganic crystal nucleus. Only when the agent and the fatty acid metal salt are blended, when only the polyamide oligomer is blended with the polyamide resin, when only the inorganic crystal nucleating agent is blended with the polyamide resin, and when only the fatty acid metal salt is blended with the polyamide resin. The present invention has been reached by discovering that an unexpected effect is exhibited.

That is, the effect of improving the strength and toughness of the obtained molded product cannot be seen by only blending the polyamide oligomer with the polyamide resin, and the extrusion deformation resistance is somewhat poor. When only the inorganic crystal nucleating agent is mixed with the polyamide resin, the toughness is poor and the extrusion deformation resistance is also slightly poor. Even when the polyamide resin is blended with only a fatty acid metal salt, the strength and toughness of the obtained molded product are good, but the extrusion deformation resistance is poor, and the polyamide oligomer, inorganic crystal nucleating agent, fatty acid When the metal salt or the like was added alone, satisfactory property improvement was not always obtained.

On the other hand, when the polyamide oligomer and the inorganic crystal nucleating agent are blended with the polyamide resin, the toughness is excellent or good, and the extrusion deformation resistance is also good.
It was also found that when a polyamide oligomer and a fatty acid metal salt are blended with a polyamide resin, the resulting molded article has excellent strength and toughness, and also has good extrusion deformation resistance.

The combined effect of the polyamide oligomer and the inorganic crystal nucleating agent or the combined effect of the polyamide oligomer and the fatty acid metal salt can be predicted at all from the results of individual addition of the polyamide oligomer, the inorganic crystal nucleating agent and the fatty acid metal salt. It wasn't something.

A polyamide resin blended with a polyamide oligomer, an inorganic crystal nucleating agent and a fatty acid metal salt is excellent in terms of crystallinity, strength, toughness of molded articles obtained, and resistance to extrusion deformation during molding. Needless to say, it exhibits excellent performance.

That is, the characteristics of the present invention are to improve the fluidity, crystallinity and releasability, and to improve the mechanical properties, especially at low temperature, by comprising a polyamide and a polyamide oligomer, an inorganic crystal nucleating agent and / or a fatty acid metal salt. Bendability at
The point is to find a material with excellent rigidity.

The present invention will be described in detail below.

Examples of polyamides used in the present invention include ring-opening polymerization products of cyclic lactams, polycondensation products of aminocarboxylic acids, and polycondensation products of dibasic acids and diamines. Specifically, nylon 6, Nylon 4.6, Nylon 6.6, Nylon 6/10, Nylon 6/12, Nylon 11, Nylon 12 and other aliphatic polyamides, poly (meta-xylene adipamide), poly (hexamethylene terephthalamide), poly ( Hexamethylene isophthalamide), poly (tetramethylene isophthalamide) and other aliphatic-aromatic polyamides, and copolymers and mixtures thereof. Particularly suitable polyamides for the present invention include nylon 6, nylon 6.6, and nylon 6/6/6.

The degree of polymerization of the polyamide of the polyamide oligomer is not particularly limited, but JIS K6810
According to the above, the relative viscosity measured at 25 ° C. in a 98% sulfuric acid concentration of 1% is 1.7 or more from the viewpoint of polymerization stability and less than 4.5 from the viewpoint of processability, particularly 2.0 or more and less than 4.0, and further .0
It is preferably not less than 3.5 and less than 3.5. The method for polymerizing the polyamide used in the present invention is not particularly limited, and melt polymerization, interfacial polymerization, solution polymerization, bulk polymerization, solid phase polymerization, and a method combining these methods can be used. Usually, melt polymerization is preferably used.

The polyamide oligomer having a limited terminal and molecular weight used in the present invention is obtained by polycondensation of lactam, aminocarboxylic acid and dibasic acid / diamine together with a molecular weight modifier. As the raw material for the polyamide portion of the polyamide oligomer, pyrrolidone, piperidone, caprolactam, enanthlactam, capryllactam, lauryllactam, glycine,
β-alanine, 4-aminobutyric acid, 5-aminopentanoic acid, 6-aminocaproic acid, 7-aminoheptanoic acid,
9-aminonanonic acid, 11-aminoundecanoic acid, malonic acid, succinic acid, adipic acid, pimelic acid, azelaic acid, phthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, ethylenediamine, 1,3 (1,2) -diamino Propane, tetraethylenediamine, hexamethylenediamine, nanomethylenediamine, undecamethylenediamine, dodecamethylenediamine, metaxylylenediamine, paraxylylenediamine, isophoronediamine and the like are used, and one or more of these are used. ..

Among the polyamide oligomers obtained from these raw materials, the polyamide oligomer obtained by the combination of dibasic acid / diamine is more preferable, and further, both or one of the dibasic acid and / or diamine has 4 or less carbon atoms. preferable.

The hydrocarbon group having 5 to 30 carbon atoms at the end of the polyamide oligomer of the present invention includes hexyl group, heptyl group, octyl group, ethylhexyl group, nonyl group, decyl group, undecyl group, dodecyl group, tetradecyl group. Group, pentadecyl group, hexadecyl group, octadecyl group, eicosyl group, cyclohexyl group, phenyl group,
Typical examples include a toluyl group, a benzyl group and a β-phenylethyl group. These hydrocarbon groups are introduced by adding a carboxylic acid and / or an amine as a molecular weight modifier during the production of the polyamide oligomer. Specific examples of these molecular weight regulators include enanthic acid, caprylic acid, undecanoic acid, lauric acid, palmitic acid, stearic acid, oleic acid, linoleic acid, cyclohexanecarboxylic acid, benzoic acid, toluic acid, phenyl. Acetic acid, hexylamine, octylamine, nonylamine, decylamine, undecylamine, octadecylamine, cyclohexylamine, benzylamine, β-
Examples thereof include phenethylamine.

The polyamide oligomer of which the terminal and the molecular weight are limited according to the present invention is obtained by heating and reacting the above-mentioned raw material of the polyamide portion and the molecular weight modifier together. The heating temperature is usually 160 to 320 ° C, preferably 180 to 300 ° C.

Although the effect of the present invention is maximized when hydrocarbon groups are added to all terminals of the polyamide oligomer, it is not always necessary that hydrocarbon groups are added to all terminals. The effect of the present invention can be obtained if a hydrocarbon group is added to at least 40% or more of the ends of the polyamide oligomer, preferably 50% or more, and more preferably 60% or more of the ends.

The polyamide oligomer used in the present invention has a molecular weight of 5000 or less, preferably 3000 or less, and more preferably 1500 or less. When the molecular weight exceeds 5,000, not only the production of polyamide oligomer becomes difficult, but also the effect of improving the releasability and physical properties cannot be obtained.
Further, the lower limit of the molecular weight is not particularly limited.

The present invention is characterized in that a specific combined use effect with an inorganic crystal nucleating agent or a fatty acid metal salt is exhibited only when a polyamide oligomer is used.

Conventionally, bisamides represented by ethylenebisstearylamide (EBS) have been considered to be effective for high cycle production. However, as shown in Examples, such bisamides are used as an inorganic crystal nucleating agent or a fatty acid. No specific combination effect with metal salts was obtained.

The present inventors have newly found an event that cannot be predicted by the conventional technique in this respect as well.

That is, in the present invention, N, N'-
It is judged that an amide of a dibasic acid and a monoamine acid such as bisstearyl succinamide and an amide of a diamine and a monocarboxylic acid such as EBS are not included in a polyamide oligomer having a limited terminal and molecular weight. It should be noted that the peculiar effect of the present invention is not lost by further combined use of an amide having a number of amide bonds represented by EBS of 2 or less in the molecule and a polyamide oligomer. Accordingly, the addition amount of the polyamide oligomer used in the present invention can be reduced without impairing the effects of the present invention.

In the present invention, the mixing ratio of the polyamide oligomer having the terminal and the molecular weight limited is 0.001 to 10 parts by weight, preferably 0.005 to 5 parts by weight, more preferably 100 parts by weight of the polyamide resin. 0.0
It is used in the range of 1 to 2 parts by weight. If it is less than 0.001 part by weight, the effect of improving various properties is not observed, and if it exceeds 10 parts by weight, fluidity and releasability are improved, but gas is generated during molding and the appearance of the molded product is improved. It is not preferable because it is damaged or mechanical properties are deteriorated.

The inorganic crystal nucleating agent used in the present invention is not particularly limited, but barium sulfate, tricalcium phosphate,
Calcium carbonate, sodium phosphate, fluorite, silicates such as aluminum silicate and magnesium silicate are preferably used. Examples of aluminum silicate and magnesium silicate include kaolin, mica, talc and the like. Particularly, talc, mica, kaolin and sodium phosphate are effective in the present invention. An increase in the crystallization rate is usually recognized by the addition of the nucleating agent. The nucleating agent has an average particle size of 10 μm or less, preferably 8 μm or less, and more preferably 5 μm or less, although not particularly limited. When the particle size is large, the reinforcing effect is reduced, which is not preferable.

The fatty acid metal salt used in the present invention is preferably a fatty acid metal salt obtained from a fatty acid having 10 or more and less than 25 carbon atoms, particularly 12 or more and less than 22 carbon atoms and a metal of Group I to III of the periodic table.

Examples of the fatty acid include stearic acid, balmitic acid, oleic acid, araginic acid and behenic acid, and examples of the metal include zinc, calcium, lithium, aluminum and barium. it can.

Preferred examples of the fatty acid metal salt include zinc stearate, calcium stearate, lithium stearate, aluminum stearate, barium stearate and the like.

In the present invention, the blending amount of the inorganic crystal nucleating agent and the fatty acid metal salt is 100 parts by weight of the polyamide resin.
0.005 to 5 parts by weight in total, preferably 0.005
To 3 parts by weight, more preferably 0.01 to 2 parts by weight. By using these, good releasability can be obtained and deformation due to the protruding pin can be prevented during molding. If the amount exceeds 5 parts by weight, the obtained material becomes brittle, which is not preferable.

The method for producing the composition of the present invention is not particularly limited, and a method of adding during polyamide polymerization, a method of adhering to the dry blend and pellet surfaces after polymerization, an inorganic crystal nucleating agent and a fatty acid metal salt during polymerization, polyamide Any method such as a method of adding an oligomer after polymerization, a method of melt kneading, a method of preparing a polyamide oligomer and a concentrate pellet of an inorganic crystal nucleating agent and / or a fatty acid metal salt by melt kneading, and dry blending the concentrate pellet May be manufactured in. As a method of melt kneading, a known method, for example, Banbury mixer, mixing roll,
Melt kneading using a single-screw or twin-screw extruder,
Mixture pellets can be obtained.

The polyamide resin composition of the present invention contains other components such as polyamide components other than the present invention, copper compounds, heat stabilizers, weathering agents, inorganic fillers, reinforcing agents, to the extent that the moldability and physical properties thereof are not impaired. Antioxidants, impact modifiers, pigments, lubricants, flame retardants and the like can be added and introduced.

The composition obtained according to the present invention is a resin composition having new characteristics lacking in the polyamide resin, without impairing the excellent characteristics originally possessed by the polyamide resin. It is most suitable for injection molding applications due to its good resistance to protrusion deformation. Products obtained by such injection molding include switches,
Ultra-small slide switch, DIP switch, switch housing, lamp socket, binding band, connector,
Connector housings, connector shells, IC sockets, coil bobbins, bobbin covers, relays, relay boxes, condenser cases, motor internal parts, small motor cases, gear cams, dancing pulleys,
Spacers, insulators, fasteners, buckles, wire clips, bicycle wheels, casters, terminal blocks, power tool housings, starter insulation parts, canisters, fuse boxes, air cleaner cases, air conditioner fans, terminal housings,
Electric / electronic-related parts such as wheel covers, bearing retainers, cylinder head covers, intake manifolds, water pipe impellers, clutch release bearing hubs, speaker diaphragms, heat-resistant containers, microwave oven parts, rice cooker parts, printer ribbon guides, etc. Car / vehicle related parts, household / office electrical parts, computer related parts, facsimile / copier related parts, machine related parts, etc. are useful for various other purposes.

[0040]

[Reference example] The autoclave with a pressure resistance of 30 kg / cm2 was charged with the raw materials shown in Table-1 and placed in a nitrogen atmosphere and sealed under pressure, 180
The temperature was raised to ° C. After reaching 180 ° C., pressure was released while maintaining the temperature inside the tube, and the pressure inside the tube was brought to atmospheric pressure over 3 hours. After this, the reaction was continued under a nitrogen stream for 1 hour while gradually raising the temperature.

After cooling, the contents were pulverized to obtain a polyamide oligomer of AF. The molecular weight of the polyamide oligomer was calculated by GPC analysis using α-chloronaphthalene or hexafluoroisopropanol as a solvent.

Aliphatic amide compounds of Comparative Examples G and H were also prepared in the same manner.

[0043]

[Table 1]

[0044]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. Each evaluation was measured according to the method described below.

(1) Tensile Properties It was measured according to ASTM D-638.

(2) Bending property The bending property was measured according to ASTM D-790.

(3) Crystallinity DSC (PERKIN-ELMER7 type) melting point (T
m) and the crystallization temperature (Tc) were measured to examine the crystallinity. The conditions were such that the temperature was raised to 20 ° C./min, Tm + 20 ° C. was kept for 5 minutes, the temperature was lowered to 20 ° C./min, Tc−20 ° C. was kept for 5 minutes, and the temperature was raised to 20 ° C./min. Sample size is about 8
It was mg.

(4) Fluidity Injection molding machine (cylinder temperature: nylon 6, 240 ° C.,
Nylon 66, 280 ℃, mold temperature: 80 ℃)
A 1 mm thick flow length test piece was molded at a resin pressure of 1000 kg / cm 2 and the spiral flow length of the test piece was measured.

(5) Releasability Injection molding machine (cylinder temperature: nylon 6, 240 ° C.,
Nylon 66, 280 ℃, mold temperature: 80 ℃)
Box-shaped molded product with pressure sensor (length 100 mm, width 60 m
m, height 25 mm, wall thickness 2 mm), and the force at the time of ejection by the ejection pin was measured by the pressure sensor, and the average of 10 shots was shown as the releasing force.

(6) Protrusion deformation resistance Injection molding machine (cylinder temperature: nylon 6, 240 ° C.,
Nylon 66, 280 ℃, mold temperature: 80 ℃)
A hat-shaped molded product (upper 2 mmφ, lower 3 mmφ, with 16 pieces) was molded, the deformation ratio at the time of protrusion by the protrusion pin was measured, and the average of 10 shots was shown as the protrusion deformation ratio.

Examples 1 to 7 Nylon 6 (ηr = 2.6) and Nylon 66 (ηr
= 2.62), the polyamide oligomer (A to F), the inorganic crystal nucleating agent, and the fatty acid metal salt are dry-blended in the amounts shown in Table 2, kneaded with a 30 mmφ twin-screw extruder, dried, and molded to obtain a test piece. It was The evaluation results are shown in Table 2.

As is clear from Table 2, a good material was obtained in which the surface appearance, the fluidity, and the mold releasability were good, and the tensile elongation did not decrease despite the high mechanical properties, especially the high rigidity.

[0053]

[Table 2] Comparative Examples 1-2 Polyamide oligomers (G-
H), an inorganic crystal nucleating agent, and a fatty acid metal salt were used in the same amounts as shown in Table 2 to obtain test pieces in the same manner as in the examples, and the same evaluation was performed.

The surface appearance was good, but the fluidity, mechanical properties, releasability, and resistance to protrusion deformation were not sufficient.

Comparative Examples 3 to 11 Evaluations were carried out in the same manner as in the Examples, but those containing a large amount of polyamide oligomer (Comparative Example 3) had good fluidity, releasability and resistance to extrusion deformation. The rigidity of the thing decreases,
The surface appearance was also poor. The composition containing no polyamide oligomer (Comparative Example 4) had lower mechanical properties than the composition of the present invention, and could not be said to have good flowability, releasability and extrusion deformation resistance. The one having a large amount of the inorganic crystal nucleating agent and the fatty acid metal salt (Comparative Example 5) had good fluidity, but had poor mechanical properties and poor appearance, and the molded product was cracked with respect to releasability, and measurement was impossible. And the protrusion deformation resistance is 100.
% Transformed. The compound containing only the inorganic crystal nucleating agent (Comparative Example 6) had good crystallinity, but no improvement in mechanical properties was observed, and tensile elongation (toughness), releasability, and extrusion deformation resistance are all good. Not to say, the good result of Example 2 from this result,
In particular, no significant improvement in toughness was predicted. The one containing only the polyamide oligomer (Comparative Example 7) is
Although the mold releasability was improved, the mechanical properties were not improved, and the extrusion deformation resistance was also 100% deformed. As a result obtained in Examples 2 and 6, the strength of the molded article and the extrusion deformation resistance were particularly high. The sex was totally unexpected. The composition containing EBA instead of the polyamide oligomer (Comparative Example 8) was generally worse than the composition containing the polyamide oligomer (Comparative Example 7). In the case of blending EBA and an inorganic crystal nucleating agent instead of the polyamide oligomer (Comparative Example 9), although the crystallinity was improved, the tensile elongation (toughness) was lowered, and the releasability and the extrusion deformation resistance were slightly improved. However, it wasn't enough. The compound containing only the fatty acid metal salt (Comparative Example 10) had improved mechanical properties, but was not said to have good crystallinity, fluidity, mold release property, and extrusion deformation resistance, and the results obtained in Example 6 Especially, the mold releasability and the fluidity were completely unpredictable. The one in which EBS and a fatty acid metal salt were blended in place of the polyamide oligomer (Comparative Example 11) was not sufficient in crystallinity, releasability and protrusion deformation resistance.

[0056]

[Table 3]

[0057]

The polyamide composition of the present invention has a fluidity,
The mold releasability is good, the molding cycle can be shortened, the productivity can be remarkably improved, and the obtained molded product has a good appearance and excellent mechanical properties.

Claims (1)

[Claims] 1. A polyamide resin (A), (B) a polyamide oligomer having a hydrocarbon group having 5 to 30 carbon atoms at a terminal and having a molecular weight of 5000 or less, (C) an inorganic crystal nucleating agent, and (D) a fatty acid metal salt. A polyamide resin composition comprising 0.005 to 5 parts by weight of (B) 0.001 to 10 parts by weight (C) + (D) per 100 parts by weight of (A).